White, Green and Cool - Maximizing the Value of Solar-Reflective Roof Membranes

Roof systems are an important element in green, sustainable architectural solutions. One of the more-interesting concepts in energy efficiency is the “cool roof,” also sometimes known as a “white” or even “green” roof. The terms are not really interchangeable -- the cool roof concept is specifically defined by the Cool Roof Rating Council (CRRC) as a roof membrane (single-ply, built-up, or modified bituminous), field-applied coating or other type roof cover, such as sheet-metal, with both a specified initial solar reflectivity and an “aged” reflectivity value. But the basic concept -- reflecting the sun’s heat, absorbing and then emitting solar radiation -- is well established.

Cool roofs are definitely green (to the extent that they are sustainable and minimize adverse environmental impact) and may contribute to interior comfort while reducing energy expenditures, but they are not the vegetated or garden-surface variety of the term “green roof.” Green roofs are also commonly designed with high insulation R-values.

The cool roof idea has been around for several decades, but it has gained importance with increasing environmental concerns. Building codes feature stricter standards regarding R-values and roof materials (e.g., thermal resistance value must be 20 or greater), while environmental issues add a social awareness element -- cool roofs can enhance your reputation.

Caveats for Cool
Cool roofs, if properly maintained, can also reduce energy costs, thus beneficially impacting an owner’s bottom line. There are some caveats regarding cool roofs, however. 

Roof surfaces should be positively sloped to minimize the accumulation of dirt in low spots and to likewise aid in “self-washing” during normal rain.  Cool roofs are particularly appropriate for warm, sunbelt-style climates like ours with greater demands for cooling rather than heating, especially for buildings with minimal thermal roof insulation. 

Targeted Maintenance
Even where a cool roof is initially effective, targeted maintenance, which is often overlooked, is still necessary for the roof to remain clean and reflective so that it can stay cool and efficient throughout its life cycle. Dirt, soot, sediment and similar substances will still settle on a cool roof to some extent making the roof darker and less efficient over time. We must invest some time, effort and money in monitoring the roof’s condition and performing cleaning or repairs as necessary. Otherwise, energy-efficiency declines and cool roof benefits are largely lost. 

Management Specialists
The best way to ensure proper maintenance of cool roof systems is our MyRAMCON Star Program (Preventative Maintenance Programs). Our programs include predictive modeling of where problems may occur, a database of various roof systems for comparison purposes, and “what-if” simulations to forecast the impact of various interventions (modify, repair, replace). We can also advise on upgrades from conventional to cool roofs, perform feasibility studies and prepare you for the challenges of altering the existing design.

Are cool roofs a cure-all for environmental and energy-efficiency challenges? No. But combined with an appropriate sustainable roof system design and an intelligent use of a MyRAMCON Star Plan through its life cycle, a cool roof can be greener and more cost-effective than other conventional alternative systems.